The best tablets on the market nonetheless feel more like interim upgrades than milestone devices worth ditching older models for

There's no question that you'll get a thrill the first time you pick up the iPad Air. It's so much more holdable, even in just one hand, than the previous full-size iPads. The new iPad has shed a quarter of the old weight, has the nicer-feeling case design of the iPad Mini, and has lost a quarter of the old volume due to its slimmer, trimmer case. The iPad Air is both a shrunken iPad and an expanded iPad Mini. Either way, it's the most portable tablet out there today.

Once the thrill of lightness and thinness passes, however, you're left with what is just an iPad.

iPad Air: Thin, light, and ... well that's itYes, like its predecessors, the iPad Air is the best tablet on the market, thanks to great hardware, a highly capable OS, and a strong ecosystem of apps and add-on devices. But the iPad Air doesn't bring much new functionality to the table. Its faster, 64-bit A7 chip and M7 motion coprocessor, which debuted in the iPhone 5s, don't add noticeable performance outside a very few applications like Autodesk's Sketchbook Pro and some games where the slight lag on an older iPad goes away in the iPad Air. The speed is entirely unnoticeable in office productivty apps, the Safari browser, and media playback apps.

It's likely that over time we'll see apps that take advantage of the A7's 64-bit processor, which has the potential to push the iPad into laptop performance range. And we'll certainly see peripherals and apps that take advantage of the M7 coprocessor. The iPad Air should get more powerful over time -- at which point there'll be a better model to buy.

The iPad Air feels more like a halfway upgrade. That's why people with spring 2012's third-generation iPad or fall 2012's fourth-gen iPad should skip replacing their iPad until a truly remarkable upgrade comes along. After all, what Apple didn't include in this year's model but did include in the iPhone 5s strongly suggests what we can look forward to next spring or fall: the Touch ID fingerprint sensor and the dual-color LED camera flash for capturing better skin tones. The iPad Air also lacks support for the 802.11ac Wi-Fi protocol, as do Apple's latest Macs. Although 802.11ac is not widely deployed today, it's on its way, and given an iPad's relatively long lifespan, today's model should be more supportive of that near-term future.

My big complaint about the iPad Air boils down to this: By the time apps and peripherals take advantage of its better processors, Apple will have a new model with more capabilities. So why not wait until then to get a new iPad? That's my strategy -- my third-gen iPad is more than capable enough for my needs today, and I'm used to its heft.

The iPad Air costs $499 for the 16GB Wi-Fi model, $599 for 32GB, $699 for 64GB, and $799 for 128GB. An iPad Air equipped with a cellular radio costs $130 more, with models available for the AT&T, Sprint, T-Mobile, and Verizon Wireless networks in the United States. The 16GB Wi-Fi iPad 2 remains available for $399; it makes sense mainly for retailers, hospitals, and others that use the iPad 2 and its Dock connector in field operations, so they need the older model still available for replacements and expansion.

iPad Mini with Retina: The higher-quality screen you can't tell apartThe iPad Mini with Retina Display is even more of an "isn't there more?" upgrade to last year's iPad Mini. It looks, feels, and weighs the same as last year's model. It too gets the new A7 and M7 processors, but again their speed isn't apparent in most uses today.

The big change to the new iPad Mini is the inclusion of the Retina display, which doubles the number of pixels. Some commentators have been whining about the lack of a Retina upgrade since the iPad Mini's debut, as from a spec point of view that made it inferior to the 2011 and later full-size iPad models.

As I noted in my review last year of the iPad Mini, its small size already brought its pixels very close together, creating an almost-Retina-quality display. Thus, I wasn't surprised that I could barely see a quality improvement in the Retina iPad Mini's display this year -- you have to look very hard to see it in small text, some zoomed-in images, and some videos. In fact, when I had people do a blind comparison of the old and new iPad Minis, most couldn't tell them apart, and those who could just as often thought the older model had the Retina display as did those who correctly identified the new model.

I wouldn't be making the display complaint had Apple not decided to raise the iPad Mini's price by $70 (the 16GB Wi-Fi model is $399, versus last year's price of $329 for the original 16GB iPad Mini). That's a big jump in price -- 21 percent! -- for minor benefit. It's even more galling when you realize that Apple did not raise the price for the iPad Air, whose 16GB Wi-Fi model costs the same ($499) as last year's model.

Otherwise, the iPad Mini with Retina Display is the same as last year's model, which makes it an unnecessary upgrade if you already own an iPad Mini. Again, you know a model in the next year or so will be more compelling.

The iPad Mini with Retina Display costs $399 for the 16GB Wi-Fi model, $499 for 32GB, $599 for 64GB, and $699 for 128GB. A model equipped with a cellular radio costs $130 more, with versions available for the AT&T, Sprint, T-Mobile, and Verizon Wireless networks in the United States. Basically, it's $100 less than an iPad Air. The original iPad Mini remains available in the 16GB Wi-Fi model for $299, a configuration best suited for children's use at home or perhaps in schools.

InfoWorld executive editor Galen Gruman analyzes the latest issues in mobile technology and the consumerization of IT. His latest book is "iPad at Work for Dummies"; Gruman has written or co-written more than 40 how-to books, on iOS, iPad, Windows 8, OS X, and desktop publishing.